For char[size], is it true that size must be constant?
Or say,will it work ?
int length;
...
char[length] arr;
Sorry,don't have the environment here so can't try it myself.
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wamp
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2This only works in C99. So you should be fine unless you're stuck with an obsolete compiler, e.g. MSVC. – Paul R Oct 09 '10 at 08:08
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2Duplicate of [Declaring an array with a non-constant size variable](http://stackoverflow.com/questions/3814719/declaring-an-array-with-a-non-constant-size-variable) and others (there may be a better duplicate question; that's just one I had at hand) – James McNellis Oct 09 '10 at 08:08
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2If it works in C99,what's different from `malloc` ? – wamp Oct 09 '10 at 08:09
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4It's `char arr[length]` not `char[length] arr`. – James McNellis Oct 09 '10 at 08:10
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So that's the essential difference between heap and stack,right? – wamp Oct 09 '10 at 08:23
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the lifetime of VLA ends when its scope ends. not when function returns... – Nyan Oct 09 '10 at 08:30
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@Nyan,so this is the most significant difference between stack and heap,right? – wamp Oct 09 '10 at 08:35
1 Answers
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Pre C99, yes; the size of an array must be a constant integral expression. C99, however, adds Variable Length Arrays (VLA's), which allow an array to have a dynamic size.
GManNickG
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If it works in C99,what's different from `malloc` ?Or say,what's different between heap and stack for C99? – wamp Oct 09 '10 at 08:11